699A - Launch of Collider - CodeForces Solution

n = int(input())
moves = input()
dist = list( map(int, input().split()) )
possible = False
first = True
time = 0

for i in range(1, n):
    if moves[i] == 'L' and moves[i-1] == 'R':
        possible = True
        if first:
            time = int((dist[i]-dist[i-1])/2)
            first = False
        else:
            time = min(time, int((dist[i]-dist[i-1])/2))

if n == 1 or not possible:
    print(-1)
else:
    print(time)